What mushroom is this? Problem?

[Mike Islander]

4' diameter live oak. Looks very healthy, with new growth on all limbs and no visible holes or caverns. No bugs that I can see. No woodpeckers.

This mushroom is 11" across. My mil says it grew over the last two weeks. Soft and pliable, like an Italian drier. Spongy on the underside.

My guess is some kind of shelf or polypore, but not an old hard mushroom (conk). Soft and fresh. Would love to ID this and also hoping it's not a bad sign for this spectacular backyard tree.

 

[Barc Buster]

Looks like a Ganoderma tsugae (reishi) mushroom. They can be slightly parasitic to living trees.

 

[Mick Dempsey]

Looks like a Ganoderma, but I’m no expert.

 

[ATH]

Another vote for Ganoderma.

 

[Mike Islander]

Wow! I knew this was the right forum for this question! My buddies on the bushcraft forum loved the photos but had no idea what it was.

 

[Reach]

I’m thinking Ganoderma as well. I’m far from a fungus expert, but I usually consider Ganoderma at the base of a tree to be bad news.

 

[KTSmith]

Well, certainly not Ganoderma tsugae, the hemlock varnish conk. Have you ruled out Ischnoderma? A few details would help. Is the top surface smooth/shiny as if it were polished or waxy like a Concord grape or furry with very short hairs? The pore surface is nice to see, but there isn't much to go on here. Could be Ganoderma, but I don't feel compelled. Of course, for those of you at home, a quick look at the spores under the microscope makes it clear, fast. Of course, we usually don't have access to that!
Also, the Chinese mycologists I know consider the ling-zhi or reishi mushroom as G. lucidum. Of course, there is some flux in the taxonomy of both mushrooms and medicine. I'm no expert here.

 

[Mike Islander]

Well, certainly not Ganoderma tsugae, the hemlock varnish conk. Have you ruled out Ischnoderma? A few details would help. Is the top surface smooth/shiny as if it were polished or waxy like a Concord grape or furry with very short hairs? The pore surface is nice to see, but there isn't much to go on here. Could be Ganoderma, but I don't feel compelled. Of course, for those of you at home, a quick look at the spores under the microscope makes it clear, fast. Of course, we usually don't have access to that!
Also, the Chinese mycologists I know consider the ling-zhi or reishi mushroom as G. lucidum. Of course, there is some flux in the taxonomy of both mushrooms and medicine. I'm no expert here.

Well, I actually do have a nice lab at my warehouse with a low power microscope. I'll grab a sample and try to get a print.

 

[KTSmith]

Ah, look for truncate basidiospores. For Ganoderma species, there will be what looks like an angular cut for the basidiospores. I'm sure there are images online! Particularly for old, dried specimens, I razor off a thin section of the pore surface, and then use the razor blade to chop up that thin section impossibly fine. Water mounts are OK, but if you have a scope and will use it, I'd recommend cotton blue stain in lactophenol. Makes the fungal cell wall pop out. The lactophenol has a lower surface tension than water so is "wetter than water" with respect to restoring dried samples under the microscope. Once again, TMI.

 

[Mike Islander]

Ah, look for truncate basidiospores. For Ganoderma species, there will be what looks like an angular cut for the basidiospores. I'm sure there are images online! Particularly for old, dried specimens, I razor off a thin section of the pore surface, and then use the razor blade to chop up that thin section impossibly fine. Water mounts are OK, but if you have a scope and will use it, I'd recommend cotton blue stain in lactophenol. Makes the fungal cell wall pop out. The lactophenol has a lower surface tension than water so is "wetter than water" with respect to restoring dried samples under the microscope. Once again, TMI.

My microscope is set up with a camera, so I'll post photos.

 

[evo]

It also doesn’t look unlike young bract form of Schweinitzii but that’s a conifer thing, and typically more yellowish

I’ve seen Schweinitzii be incredibly variable

 

[KTSmith]

I'd first exclude Ischnoderma. True that schweinitzii is highly variable with respect to the amount of yellow, but yes, a conifer thing.